https://github.com/yehiasharawy/modified-sic-onepassassembler

The one-pass assembler will read the assembly code, allocate memory, and generate the corresponding relocatable machine code for execution on modi-SIC. It will handle symbol resolution, directive processing, and object code generation (HTE) in a single pass.
https://github.com/yehiasharawy/modified-sic-onepassassembler

java modi-sic modi-sic-assembler sic sic-assembler

Last synced: 6 days ago
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The one-pass assembler will read the assembly code, allocate memory, and generate the corresponding relocatable machine code for execution on modi-SIC. It will handle symbol resolution, directive processing, and object code generation (HTE) in a single pass.

• Host: GitHub
• URL: https://github.com/yehiasharawy/modified-sic-onepassassembler
• Owner: YehiaSharawy
• Created: 2023-12-01T15:28:46.000Z (about 1 year ago)
• Default Branch: master
• Last Pushed: 2023-12-16T17:33:48.000Z (about 1 year ago)
• Last Synced: 2025-02-08T19:45:55.458Z (6 days ago)
• Topics: java, modi-sic, modi-sic-assembler, sic, sic-assembler
• Language: Java
• Homepage:
• Size: 37.1 KB
• Stars: 2
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Modi-SIC One Pass Assembler

It is a program that performs one-pass assembly for the Modified Simple Instruction Computer (modi-SIC). 
 

The assembler will translate assembly code into machine code compatible with the Modified Simplified Instructional Computer. 




The modi-SIC architecture retains the instruction set and Format 3 instructions from the original SIC (Simple

Instruction Computer). 
It also includes the concept of reserving variables in memory using directives such as

BYTE, WORD, RESB, and RESW.

### Key Modifications and Extensions:

• Format 1 Instructions: Modi-SIC extends its capabilities by introducing Format 1 instructions,expanding the range of supported operations.



• Immediate Instructions (Format 3): Modi-SIC introduces immediate instructions, allowing for the handling of immediate values passed as integers. This provides greater flexibility in executing instructions.



• Relocation: The Modi-SIC also supports relocation by using the masking bits in the text records, where 1 denotes memory location that needs modification and 0 otherwise.

### Instructions Handling:

The assembler will process the assembly code in a single pass, generating machine code (HTE records) for execution on the modi-SIC. It will consider both the original SIC Format 3 instructions and the newly introduced Format 1 instructions and immediate instructions

# Instruction Set



# Instruction Format

## Format 1

|OPCODE (8 Bits)|

|---|

## Format 3

All Type 3 instruction could be immediate instructions this is done by a new division of bits of instructions of Type 3 (Format 3) as shown in following table.

|OPCODE (7 Bits)|Immediate Flag [i] (1 Bit)|Indexing Flag [x] (1 Bit)|Address (15 Bits)|

|---|---|---|---|

The modification applied on the opcode as



Only opcode is represented as 7 bits (not 8) as in SIC

The 8th bit of the opcode represents the immediate flag (i) which has two value



a. 0 if the instruction without immediate value (has an address) 


b. 1 if the instruction with immediate value





# Implementation

### Input

It takes as an input a text file (in.txt) that contains modi-SIC assembly program. 


Remember that The modi-SIC program includes Format 1 instruction of SIC/XE.

### Output

A generated symbol table file (symbolTable.txt) for all the symbols extracted from the program.



A generated complete HTE records (objectcode.txt) which contain ne header, one or more text records (including masking bits) and one end record.